Zhengzheng (Jing Liang) travels from her home in northern China to Dongguan with her eight-year-old autistic son Xinxin (Jiangdi Zhu) in the hopes of finding the boy's father. She takes a job in an assembly line at a fan factory while Xinxin stays at a community home.
Son of the Stars contains examples of:
- Broken Record: Xinxin repeatedly chants "Noodles!" while Zhengzheng takes him to a restaurant to eat pork noodles.
- Dedication: "To all the children with special needs and their parents."
- Disappeared Dad: Xinxin's father left when he was eighteen months old, when his parents realized he was autistic.
- Eyes Always Averted: Xinxin rarely looks people in the face, and closes his eyes when people try to force eye contact on him.
- Parental Abandonment: At an amusement park, Zhengzheng deliberately lets go of the rope that keeps Xinxin from running away, feeling like he's her greatest obstacle to happiness. Later, she comes to greatly regret it. She files a police report and is told that she could spend three years in jail for willful abandonment. She also prints Missing Child posters.
- Self-Harm: Xinxin bites himself aggressively on the wrist. When he's missing, Zhengzheng bites herself hard enough to draw blood.
- Sleeping with the Boss: Zhengzheng starts a relationship with her supervisor Hong Jin (Wei Xin), who gives her a promotion, to the anger of some of her coworkers, and lets her move into his nice apartment. They break up because he doesn't want an autistic stepson.
- Struggling Single Mother: Zhengzheng sleeps in a dorm at the factory and takes as much overtime as she can to pay for Xinxin's expensive placement at the community home.
- Symbolically Broken Object: Zhengzheng rips apart a picture of herself and Xinxin with her husband. She later tapes it back together.
- Tears of Joy: Zhengzheng cries when she finds Xinxin among the missing children at the police station.
- The Unintelligible: Xinxin sometimes says short phrases, but he mostly mutters unintelligibly.